A New Sound Standard
Radio production no longer only requires the technical skill of making radio spots and promos.
In the modern radio production facility we are also involved in mixing audio soundtracks for television, the internet, outside and in-store broadcast.
For many years one of the number one complaints by the audience to television companies has been, “The ads are too loud!” In the early 2000’s this issue had caused enough noise that politicians became involved and set up various committees of professional sound engineers, technicians and broadcast heads who were tasked with finding a solution.
Fast forward 10 years … and on January 1, 2013 a new audio standard was introduced to address the excessive loudness of TV commercials vs TV programmes.
I asked some audio professionals involved with mixing radio and television audio to tell us more about this new standard and how they are working in the studio to ensure their mixes fit with the new rules.
Darren ‘Robbo’ Robertson owns and runs Voodoo Sound.
Daryl: Tell us about OP59 from a technical perspective …
Not a bad idea in general, but that was its biggest problem, it was TOO general.
Wording such as “Compression should be used appropriately” and “limiting must not be used for the purpose of producing excessively noisy or strident material” left it wide open to personal interpretation, and didn’t really change anything in terms of on-air sound.
OP59 builds on OP48, and makes the parameters a lot more specific. It deals directly with the perceived loudness of a commercial. It also brings us into line with U.S. and European broadcast specifications. Put simply, it essentially measures the ‘loudness’ of the sound track over time.
Before this gets too hard to understand, it’s important to remember that loudness and level are two different things. If two different audio tracks are played back to back, even though their levels are the same, one can (and usually will) sound louder than the other. Loudness monitoring uses an algorithm to display, (in LKFS), the loudness of a track as perceived by the human ear over time, not just at a given frame.
OP-59 requires all audio to be -24LKFS. Any audio above this level may be rejected by the broadcasters from January 1, 2013.
Jamie Greene is the owner of Speed Of Sound in Sydney and has a background in radio and television production having worked at 2DAY in the 90’s.
Jamie: It’s important to note that only Free to air are adopting the OP59 standard at the moment, although I suspect Foxtel and other providers of commercial content won’t be far behind. They still use OP48 which is governed by a reference of 1k tone=-20ppm so zero VU is around -9.
It means we are mixing to an absolute maximum allowed number i.e.-24 LKFS. We are not permitted to go above this absolute.
Also, from what I can gather so far, using "brick wall" type limiting is no longer really necessary. There is not a huge amount of difference between a commercial mixed to OP48 compliance and OP59.
Daryl: What does it mean for the audio engineer when mixing for TV?
Jamie: It means we are mixing to an absolute maximum allowed number i.e.-24 LKFS. We are not permitted to go above this absolute.
Robbo: Firstly it means that there is less reliance on the limiter, and compression needs a little more thought, but on most mixes it’s not really a lot different.
Dennis Guthrie is the Head of Vision and Audio for SCA on the Gold Coast.
Daryl: What new plugins or gear should be used to accurately monitor/process?
Dennis: We are currently reviewing across the group a number of plug-ins for pro tools that will make sure our mixes are OP59 compliant.
I don’t envisage changing the mastering process too much as I advise all the guys to go for a really natural sound when mastering. If you are using your ears, compression and limiting correctly you will achieve a great all round sound for television.
Once again the best way to adjust your mix is to monitor some of your work on the end medium, be it radio or television etc.
There will be very few radio and TV production suites outside of metro stations that have been truly acoustically designed so you know that everything you are mixing is accurate.
In my experience there has only been 3 Studios that have truly represented a true sound no matter where the end material was played.
A lot of people don’t place enough importance on acoustic design.
Jamie: There are a plethora of plug-ins out there that fit the bill by respected vendors – but the 2 I rely on are the TC electronic LM 2.
My personal fave is the LM correct because you can batch process and get things ‘spot on’ without the fiddly process of tweaking to the maximum number. (The algorithm isn't as linear in response as you might think! It differs in response according to the content you're mixing so for pretty fast mixers like me it can be a right royal pain in the butt!)
Robbo: There are a number of meters on the market, both plug in and rack mounted. Make sure that the ones you buy conform to the Australia & New Zealand standard (we are using the BS.1770-3 standard).
I’m using the Waves loudness meter. I like it because it’s easy to read and is easily configured. But there are a heap of plug-in alternatives, from companies like T.C. Electronics (the LM6) and the Dolby media meter 2.
A mate of mine is using the Izotope Insight meter. He tells me that it drops a marker on the automation channel of the plug-in when you have an ‘over’ so you can go straight back to it and correct it before a final mix.
Whichever way you go, it’s important that the meter is set up properly before you trust your mix to it!
Almost all will need to be setup as recommended by CAD's OP-59 documentation, and some are easier than others.
Many thanks to Darren Robertson, Jamie Greene and Dennis Guthrie for their time and knowledge.